The Vital Role of Acoustic Seals
Acoustics is the science of sound and the correct acoustic seals for doors or windows are necessary to provide a barrier against sound and unwanted noise. DSA have developed and many acoustic seal combination systems and have had them tested to achieve acoustic ratings, which can be then used to suit the individual requirements of a building, room, or door assembly.
DSA Acoustic Seal System Testing
A series of comprehensive tests to establish the airborne sound insulation performance of DSA acoustic seals have been conducted in accordance with: AS1191 / ISO 140-3 / EN ISO 10140 .
How DSA Test for Acoustic Sealing Performance
DSA sealing systems are acoustically tested in their normal everyday operational mode under laboratory
conditions. To evaluate the door assembly acoustic efficiency, DSA conduct a series of three tests:
No Seals – A test with the gaps around a door unsealed, also known as un-caulked. This provides the
minimum level of performance a door can achieve with no seals.
With DSA Seals – The same door is fitted with DSA seals around the full perimeter and re-tested to
determine the acoustic performance improvement.
Fully Caulked – The gaps around the door perimeter are sealed with a high density acoustic putty and retested
to determine the maximum possible acoustic performance of the door assembly.
By comparing these three test results it is possible to determine and rate the sealing system efficiency and
maximum potential performance of a door assembly under evaluation.
The Rating Systems DSA Use to Measure Acoustic Seal System Performance
STC – Sound Transmission Class
The noise performance of a building structure is called the Sound Transmission Class (STC). It is calculated from 1/3 octave band sound transmission loss data by a method described in American Society for Testing Materials (ASTM E316). The higher the STC the better the structure is at isolating airborne noise. An STC rating of 45 means that the sound passing through the building is reduced by 45dB.
Rw – Weighted Sound Reduction Index
Rw was developed by the International Standards Organisation (ISO), it uses a slightly different frequency range (100-3150Hz versus 125-4000 Hz for STC). In general, STC or Rw give either the same rating result number, or just only 1 to 2 points’ difference.
The following table is a guide for matching your acoustic environment needs with an STC/Rw rating:
| STC/Rw | Performance | The Effect on Speech Perception |
| 53 | Excellent | Loud speech cannot be heard |
| 48 | Very Good | Loud speech can be barely heard |
| 456 | Better | Must strain to hear loud speech |
| 42 | Good | Loud speech heard as a murmur |
| 35 | Okay | Loud speech can be heard but not understood |
| 30 | Fair | Loud speech can be heard easily |
| 25 | Poor | Normal speech can be heard easily |